I think the main reason is that if we reach that limit of knowledge, we will always be left with the question, "How did something come from nothing?" I don't know if humans will ever be able to explain that question as it's not something we can experience. That naturally lends itself to the conclusion that there is something greater than us in the universe that can manipulate the physical world we observe in ways we do not understand. Whether that is the colliding of multiverses or divine intervention we wouldn't and couldn't ever know.